The breakdown voltage requirement in semiconductor devices can range from a few volts to more than 10 kV, depending on the application. Referring to FIG. 1, the breakdown voltage is typically supported across a depletion region 120 of a semiconductor device, which is an insulating region within the device where the charge carriers have diffused away or have been forced away by an electric field. The depletion region 120 is typically formed between a p-doped region 130 and an n-doped region 110 (p-n junction) or at a metal semiconductor (Schottky) interface (not shown). The breakdown voltage is the maximum voltage that can be applied across the depletion region 120 of the device before the depletion region 120 collapses. For optimum device performance, the breakdown voltage of the device should be as close as possible to the intrinsic capability of the underlying semiconductor material.
The breakdown voltage of the device is often reduced by the occurrence of high electric fields either within the interior portion of the device or at the peripheries, i.e., edges, of the p-n junction or the Schottky interface. In particular, electric field crowding at these peripheries leads to premature voltage breakdown and adversely affects the breakdown voltage capability of the device. Referring again to FIG. 1, an edge region 140 represents electrical field crowding that reduces the breakdown voltage of the device.